1. Field of the Invention
This invention relates to a connection structure for connecting a wire and a terminal by ultrasonic vibration and by ultrasonic wave oscillation, a connection method thereof and a terminal for use therein.
2. Description of the Related Arts
FIGS. 1 to 5 show a conventional connection structure by ultrasonic vibration described in Japanese Patent Application Laid Open No.Hei7-320842.
In connection structures shown in FIGS. 1 to 5, a pair of resin chips 2 in which soldering material 1 such as solder is filled or installed are used, and covered wires 5 the cores 3 of which are covered with each covering portion 4 intersect each other and are joined with each other. That is, as shown in FIG. 1, the intersecting portion of the covered wires 5 is pinched with a pair of the resin chips 2 from up and down. A ultrasonic horn (not shown) is fit to the resin chip 2 so as to apply a pressure to the intersecting portion. With this condition, ultrasonic waves are applied from the ultrasonic horn, so that as shown in FIG. 2, the resin chips 2 are melted and fused together. The covering portion 4 of the covered wire 5 is melted and removed so as to expose the cores 3. At the same time, the soldering material 1 is melted by heat generated when the chips 2 are melted, so that the exposed cores 3 are soldered with each other.
In connection structures shown in FIGS. 3, 4, resin chips 6 in which the soldering material 1 is buried such that its top is exposed are used. The resin chips 6 are contacted with the intersecting portion of the covered wires 5 such that the soldering material 1 is in contact therewith. By melting the resin chips 6 and then melting and removing the covering portion 4, the intersecting cores 3 are soldered with each other by the soldering material 1.
In a connection structure shown in FIG. 5, a terminal metal 1 is connected to a covered wire 5. According to this structure, one resin chip 8 having the soldering material 1 is placed on an anvil 9 and then the terminal metal 7 and covered wire 5 are placed on the anvil 9 such that they are made in contact with each other. Then, the other resin chip 8 is contacted with the covered wire 5. By carrying out ultrasonic vibration by the ultrasonic horn 10, the covering portion 4 is melted and removed. At the same time, the resin chip 8 is melted and the soldering material 1 is melted so as to connect the cores 3 to the terminal metal 7.
However, because the resin of the covering portion 4 and resin chip 2 exist between the intersecting cores 3 in the connection structure shown in FIGS. 1, 2, even if the soldering material 1 is melted at the same time as the melting of the resin, the melted soldering material is obstructed by the resin, so that it cannot make an excellent contact with the cores thereby the connecting reliability being reduced.
In the connection structures shown in FIGS. 3 to 5, the melted soldering material 1 is expelled outside of the connecting portion together with a melted portion of the covering portion 4 of the covered wire 5, so that the reliability of the connection is also reduced.